Insulated conductor construction



9 Sheets-Sheet l C. W. ABBOTT Filed Oct. 25, 1941 Nm. Wm

INSULATED CONDUCTOR CONSTRUCTION Oct. 31, 1944.

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INSULATED CONDUCTOR CONS TRUCTION Filed Oct. 25, 1941 9 Sheets-Sheet 4 INVENTOR 2.5 CIL/Hemels M/Zgeaff BVMW@ ATTORNEY Oct. 3l, 1944. c. w. ABBOTT INSULATED CONDUCTOR CONSTRUCTION 9 Sheets-Sheet 5 Filed Oct. 25, 1941 9C C9 Lv 7 a M /N M n Z @v5 T MM 9 e 2 ya. 7H. e g 2 @X2 d f l I .,i Z l g m02 x Z @6 5 Z 9 2 Z Z z c c 6" 7 7? y Z Z fwn/WZ Oct. 31, 1944. C;l w ABBOTT 2,361,374

INSULATED CONDUCTOR CONSTRUCTION v Filed Oct. 25, 1941 9 Sheets-Sheet 6 Oct. 31, 1944.

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INSULATED CONDUCTOR CONSTRUCTION Filed Oct. 25, 1941 9 She'ts-Sheet 7 NVENTOR kaza s d [465077 ATT Oct. 31, 1944. c. w. ABBOTT INSULATED CONDUCTOR CONSTRUCTION Filed Oct. 25, 1941 9 Sheets-Sheet 8 INVENTOR @Haags 4J vf mlm mm Oct. 31, 1944. c. w..ABBoTT INSULATED CONDUCTOR CONSTRUCTION 9 Sheets-Sheet 9 Filed Oct. 25, 1941 W, M, l

Patented Oct. 31, 1944 UNITED STATES PATENT OFFICE INSULATED CONDUCTOR CONSTRUCTION Charles W. Abbott, Larchmont, N. Y.

Application October 25, 1941, Serial No. 416,451

42 Claims.

This invention relates to insulated conductor construction for use in electrical circuits.

One of the objects of this invention is to provide a dependable and efficient insulated electrical conductor construction utilizing, as an insulating v casing or insulating covering to insure adequate range of relative movement therebetween as is desirable in certain uses, handling, or installations,

Another object is to provide a practical and inexpensive method of constructing insulated conductors with synthetic materials of the abovementioned character and which will be readily adaptable or variable according to the practical requirements of the conductor construction and according to various of the characteristics or properties of such synthetic products. Another object is to provide a practical and elicient method of producing insulated conductor construction of the above-mentioned character with the synthetic that is to form the insulation being initially in sheet or strip form. Another object is to provide a practical and dependable method for insulating an electrical conductor or conductors with a thermo-plastic strip or sheet insulating material, that may be readily carried on, on a commercial scale. Another object is to provide a practical and commercially feasible method of applying, in initially strip form, thermo-plastic materials to an electrical conductor or conductors to form the entire or part of the insulation therefor, and to achieve insulation of a conductor or conductors, in the just-stated manner, without detrimental reduction or variation in wall thickness of the applied insulation.

Another object is to provide a practical and reliable method of applying insulated compound in strip or sheet form to one or more electrical conductors, to form the entire or part of the insulation therefor, in a manner to provide and maintain such physical relationship between the CFI conductor or conductors and the insulation as will permit relative movement therebetwen and thus to facilitate installation and handling of the conductor construction, particularly where it embodies more than one conductor, and thus also avoid detrimental compounding of strains either in the conductor or conductors, or in the insulation, or both. Another object is in general to provide an improved and practical method of making insulated conductors.

Another object is to provide simple, practical and dependable apparatus for carrying out the above-mentioned method or methods.

Other objects will be in part obvious or in part pointed out hereinafter;

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts and in the several steps and relation and order of each of the same to one or more of the others, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in which are vshown several of the possible embodiments of the mechanical features of my invention,

Figure 1 is a side elevation, partly in vertical section and partly diagrammatic, of one form of apparatus;

Figure 2 is an end elevation as seen along the line 2-2 of Figure 1;

Figure 3 is an end view, partly in section, showing one form` of iiuting device;

Figure 4 is a plan view as seen along the line 4-4 of Figure 3 of the fluting device;

Figure 5 is a sectional View along the line 5 5 of Figures 3 and 4 showing the action of the uting device;

Figures 6 and 7 are, respectively, views like that of Figure 1, but showing other and simpler forms of apparatus;

Figure 8 is a fragmentary or partial vertical transverse sectional view as seen along the line 8-8 oi' Figure l, indicating a preliminary relationship between conductors and sheet insulating material;

Figures 9 and 9a are similar transverse vertical sectional views as seen along the line 9-9 of Figures l, 6, 7 and 25, showing certain preferred structural features of the apparatus and indicating certain possible dimensional relationships therebetween and the materials operated upon;

Figure 10 is a fragmentary detached plan View as seen along the line lll--I of Figures 1, 6, 7

and 25, showing a form of slitting or parting and sealing arrangement;

Figures 11, 12, 13 and 14 are transverse fragmentary sectional views, on an enlarged scale, of the conductor constructions in certain preferred sequences or stages of carrying out in practice one form of my method and apparatus;

Figure 15 is a transverse fragmentary sectional view, on an enlarged scale, showing how, for example, paired conductors may be constructed;

Figure 16 is a view like that of Figure 9 illustrating a different conformation of certain of the elements;

Figures 17 and 18 are transverse fragmentary sectional views, like Figures 11 and 12, of the conductor constructions, illustrating certain steps and features of construction resulting therefrom;

Figure 19 is a view like that of Figure 9 showing a modified configuration of certain of the parts of the apparatus;

Figure 20 is a transverse fragmentary sectional view on a large scale showing the conductor structure resulting from the apparatus of Figure 19;

Figure 21 is a view like that of Figure 20 show ing a modified form of conductor structure and apparatus;

Figure 22 is a transverse sectional view on a large scale showing a conductor structure resulting from carrying further certain aspects of my method;

Figure 23 is a plan view showing diagrammatically certain of the steps for producing the structure of Figure 22;

Figure 24 is a transverse sectional view on a larger scale as seen along the line 24-24 of Figure 23;

Figure 25 is a View like Figure 1 illustrating another mode of carrying on my method and showing an illustrative apparatus for so doing;

Figure 2.8 is a view like that of Figure l2 showing, in fragmentary transverse section on an enlarged scale, a conformation of certain of the elements for effecting or facilitating parting;

Figure 27 is a transverse sectional view as seen along the 21-21 of Figure 26; and

Figure 28 is a fragmentary plan view showing the insulated multiple conductor structure resulting from the steps and apparatus of Figures 26 and 27.

Similar reference characters refer to similar parts throughout the several views of the drawings.

It has heretofore been proposed to insulate one or more electrical conductors by rolling or pressing, longitudinally thereof and from two semi-circular sides thereof, two strips of natural rubber with the inner faces thereof bearing a cement or with one or both of them of unvulcanized rubber, or by rolling or pressing two sheet materials like fabric, paper or the like, bearing an adhesive or other cement on their inner faces, whereby the strip material is compressed tightly all around the conductor or conductors and becomes bonded together and to the conductors, either by the cement, adhesive, vulcanization or otherwise, but I am unaware that any such proposals have proven practicable or commercially successful, excepting for so-called strip insulation where two strips of vulcanizable rubber ar rolled or pressed around and against the two sides of conductors and thereafter vulcanized by methods which are slow, cumbersome and expensive, limiting the resultant construction to a considerable degree. Additionally, the insulated conductor or conductors that result from carrying out such proposals are deiicient for numerous reasons, rendering them impracticable for numerous important uses and installations, and among them may be mentioned the difficulty or impossibility, particularly with natural rubber, of achieving, by the proposed methods, consistent uniformity of wall thickness; the costliness of carrying out commercially certain of these proposals; the virtual impracticability of commercially practicing such proposals with the use of natural rubber utilizing cements; the expense and additional cumbersome processing where vulcanization is used to secure bonds; and also the fact that the bonding of the insulating covering to the conductor or the tight enclosure by the covering of the conductor prevents freedom of movement therebetween during bending or the like, with the result that strains are set up in the conductor or the insulation or both, which strains when compounded by multiple bending may result in insulation rupture or breaking of conductor strands. One of the dominant aims of this invention is to provide a practical and economical insulated conductor construction utilizing sheet or strip materials in a manner and by methods which will avoid the deficiencies and disadvantages of such prior constructions and have other useful superiorities thereover, and to provide a. practicable method and apparatus for making possible the utilization of certain insulating materials, heretofore considered impossible of such use, in sheet or strip form, in the quantity production of insulated conductor.

Furthermore, and as is well known, ordinary rubber compounds as used for insulating wire have a number of inherent characteristics which are disadvantageous when used for the insulation of conductors; thus, for example, rubber is detrimentally affected by various oils and by petroleum products, it oxidizes, it deteriorates under the action of sunlight and it burns freely, and hence, either corresponding precautions have to be taken in the use or application of rubber-insulated conductor or special provisions have to be made structurally to effect protection of the rubber itself. For example, in electrical Wiring construction such as the type that utilizes boxes, such as outlet, junction and distribution boxes, wherein considerable numbers of rubber insulated conductors are present, the conductor employed has over its rubber insulation a covering, usually made of asbestos or fabric serving or braid, so saturated and treated as to be resistant to fire which may originate in such boxes from various causes. There are, however, a number of materials lacking such deficiencies as those just mentioned in connection with rubber and which, moreover, are supperior to rubber in other respects in that, for example, they are tougher and stronger, do not damage aseasily as rubber, are more resistant to blows, abrasions. tearing strains and the like, and can be employed in lesser thicknesses for insulation purposes than rubber, and yet have not been found thus far capable of general use in the insulation of conductors upon a basis commercially practicable or upon a reasonable cost basis, or both, excepting in special and usually costly constructions.

Among such materials are the so-called synthetic rubbers, and like or analogous synthetic formulations and of these there are certain particularly desirable materials that are recognized as being non-vulcanizable and which, while pliant and having broadly other physical properties of natural rubber, are thermo-plastic, and it is ,these which I have discovered may be processed, according to my method, in conjunction with a conductor or conductors to produce, on a basis of reasonable cost and commercial feasibility, insulated conductors capable of wide uses and applications far beyond those of the few costly and special insulated conductors thus far produced with the aid of synthetic products. l

Among the unvulcanizable synthetic materials having thermo-plastic characteristics suitable for processing according to my invention, I prefer to employ, and set forth as examples or illustrations, plasticized vinyl chloride polymers, such as those known and available on the market as Koroseal and Flamenol and Korogel, polyvinyl acetate, such as is known under the tradename Formvar and polyvinyl ychloride-acetate, such as is known under the tradename as Vinilite, and isobutene polymers, such as is known under the tradename Vistanex. These materials, moreover, can be produced in sheet or strip form of substantial lengths, as in rolls, and in suitable thicknesses, preferably thicknesses on the order of 0.010 or 0.050", according, of course, to the insulating and other properties which are desired in the insulated conductor construction, and hereinafter I refer to these materials, or their comparable equivalents, as sheet material or strip material.

How I process, with a conductor or conductors, materials such as those just mentioned and which are non-vulcanizable and have thermo-plastic characteristics, will be better understood and grasped if consideration is first given to a possible form of apparatus, that of Figure 1, for example, that may be employed in carrying out one form of my method, and in this form of apparatus, the latter may comprise a suitable frame having suitable side frames or standards 20 and 2| provided with suitable means, such as detachably mounted spindles 22, 23, for supporting rolls 24 and 25, respectively, of the strip or sheet material to be employed. The latter may be of any suitable width, as viewed in'Flgure 2, usually depending upon the number of conductors and their diameter which are to be simultaneously covered, and in length, the material may be of any suitable dimension.

The web or sheet material of the rolls 24 and 25 I arrange to draw off of the latter and into juxtaposition to each other, vbut with the conductors to be covered drawn along with the ends of the webs, in between the latter, and at the same speed, and that three-element entity I then bring into the zone of action of two co-acting heater and presser elements, preferably taking the form of rollers or drums 25 and 21, (Figures l, 2, 6 and '7) and certain preferred features of construction and action of which are later described, though it may, at this point, be noted that the drums 25--21 are heated in any suitable way as illustratively later described.

Depending upon various factors, such as the particular thermo-plastic characteristic of the sheet or web material, its thickness, the'diameter of the conductor or conductors to be covered, the rate or speed of action of the elements 28 and 21 upon the web material relative to the conductors, I may find it desirable, in effect, to partially preform the web material or somewhat preheat it, or both, and where both such steps are desirable, I may utilize a form of apparatus like that shown in Figure 1.

Thus, I may arrange drum 21 above drum 26 and, in such case, I prefer to mount the web roll 25 at an upper portion of the frame' and web roll 24 at a lower portion of the frame (see also Figure 2), and guide the sheet or web material into proximity to the heated drums so as to become warmed thereby, to substantially the desired extent. Thus the sheet or strip material 28 from the roll 24 may be passed about guide rollers 30, in suitable number, and which are preferably arranged substantially along an arc whose center may be at the axis of drum 26 and whose radius is sufficiently greater than the maximum radius of drum 25 so as to guide the moving web 28 at the desired distance from the heated drum and about a substantial arcuate extent thereof to become warmed by heat emanating from the drum, thus to give the web material better pliancy for the subsequent steps. In similar manner, web 29 from the roll 25 may be guided over similarly positioned guide rollers 3|, but spaced about a substantial arcuate extent of the upper drum 21, thus to improve the pliancy of the material for the subsequent step. Where such an arrangement is utilized, waste of heat from the two operating drums is diminished.

For preshaping the moving web material, thus initially warmed, where that step is desirable, I provide suitable means for, in effect, longitudinally iluting the two webs and a preferred form of apparatus for so doing comprises a lower device, generally indicated by the reference character 34, for operation upon the lower web 28 and an upper device for operating upon the upper web 29; I'hese devices are preferably of identical construction and hence only one need be described in detail, though in relation to the operating throat formed between the drums 26- 21, the one device is inverted relative to the other. Each has an entry end for the web material, at its right hand end as seen in Figure 1, into which the web enters in flat or plane condition, and an exit end at its left hand end and adjacent the operating portions of the drums 2li-21, the webs emerging from the left hand ends longitudinally corrugated or iluted and with the transversely spaced conductors therebetween, in the general relationship indicated in Figure 8, where the conductors are shown at 35.

I'he two devices 34 and 35 each comprise two sets of companion iiuting elements 40 and 4| (Figures 3, 4 and 5) which, in the illustrative form, may be made of relatively stiff, but somewhat springy, wire of a diameter commensurate with the diameter of the conductors 36 and, in such case, may be given a shape and mounting as shown in Figure 4.

Thus the upper set of fluting elements 40 are mounted in any suitable way to be parallel to each other, as for example, by securing them to a rod 42 mounted in any suitable way in the side frames 20, 2|, preferably adjustably in a direction toward or away from the companion fluting elements 4| and preferably also about the axis of rod 42, as indicated by the arrows in Figure 3; from the rod 42 each iiuting element has a substantially elongated and slightly curved portion 40 terminating in a bent-over front or leading portion 40, and the spacing of the elements 40 crosswise of the web and hence lengthwise of the supporting rod is preferably equal and on the order of the spacing desired between the several conductors.

In a similar manner, though inverted, as better appears in Figure 3, iluting elements 4l are mounted on a supporting rod 43, adjustable toward or away from the rod 42 and preferably also about its axis, as indicated by the arrows, each element 4| having an elongated, somewhat curved, portion 4l` and a curved over or leading portion 4Ib. Elements 4l* are also parallel to each other, spaced according to the spacing desired between. the several conductors, but the assemblage of the two parts of the flutng device 42-40 and 43-4I or the mounting of the uting elements on their respective supporting rods is such that elements 4B alternate with elements 4| and each extends centrally between two adjacent elements of the other, as is better shown in Figure 4. The setting or adjustment, as by setting or adjusting either or both of members 42 and 43 is somewhat as indicated in Figure 3, so that as the web is drawn in between the two sets of fiuting elements 40 and 4|, the web becomes interrelated thereto, as is better shown in Figure 5, becoming longitudinally fluted or corrugated as it moves along.

The leading curved ends 40b and 4Ib insure smoothness of initial action of the fluting elements upon the moving web material and the portions 40a and 4 la thereof may be initially bent or curved to eilect a progressively deeper or greater iluting action as the material progresses from the leading ends thereof toward the rear ends.

Preferably, also, the uting elements are arranged to have eiective uting portions positioned, at least at their forward or leading ends, in the shape of a V, with the apex aligned with the center line of the moving web material and pointing in the direction from which the material feeds, as for example, toward the guide roller to the right of the fiuting device, as seen in Figure 1.

Such an arrangement assures that the fiutings in the mov'ng strip or web material are successively formed from its center line outwardly in both directions, thereby avoiding harmful straining or stretching or distortion of the web material, the overall width of which, when it emerges from the fiutng device, being, of course, less than its initial width. Also, and depending upon various factors, where partial preheating is employed, the fiuting action is facilitated or eased by the increased pliancy of the web material resulting from preheating. The depth of the iiutes or corrugations and also the rate of progressive uting action of the iiuting elements to either side of each web may be determined by adjustment of the two sets of iluting elements (see Figure 3), toward or away from each other or by varying the settings thereof about the axes of the mounting rods 42 and 43, or both.

The two fluting devices 34-35 are related to each other in the general manner shown in Figure l, that is, with the one inverted relative to the other, and it is through the space between the two devices 34--35 that the conductors 36 Y are moved or drawn in a direction toward the left as viewed in Figure l, and for greater convenience of access and of arrangement, the devices 34-35 and hence their parts may be given an inclination relative to the plane along which the plural'ty of conductors 36 are moved toward the left, the plane of movement of the parallel spaced conductors 36, in eiect, bisecting the angle formed by the two devices, with the conductors emerging at the apex of that angle.

The conductors 36, which may be solid or stranded wire, are supplied from respective reels diagrammatically indicated at 5| and, respectively, provided with suitable braking means or the like to give each conductor 36 the desired tautness or tension. Preferably also, suitable means such as a guide comb, diagrammatically indicated at 52, are provided to ilx thespacing between whatever number of conductors 36 are to be treated, and here the spacing is related to the iiuting effected by the ilutlng devices 3l and 36, or vice versa, and the tluting effected by device 34 is the reverse of the iluting efl'ected by the device 35, the relationships being better shown in Figure 8 from which it will be seen that, as the conductors 36 emerge from or pass through the apex of the angle between the two fiuting devices of the fluting assembly 34-35 with the now iluted web 29 above them and the now fiuted web 28 below them, the interiorly concave portions of the two webs 28-29 face eachother and each pair of such juxtaposed concave portions of the two webs has therebetween a single conductor 36.

Suitable means may be employed to vary the warming effect upon the sheet material by the drums as, for example, by changing the spacing of the rollers 3| and 3l, respectively, from the drums 21 and 26, and for this purpose, these rollers may be mounted adjustably by any suitable means not shown, but indicated by the arrows in Figure 1.

Where various factors, such as those indicated earlier above, do not require iluting or'pre-shaping of the sheet material, the fluting devices 34 and 35 may be omitted, whence the arrangement shown in Figure 6 may be employed where it is still desired to warm up the sheet material, as by letting it obtain heat from the respective drums, Also, there can be present factors which do not require either fiuting or pre-warming and, in such case, I may eliminate these two steps and the corresponging fluting and heating means, leaving the apparatus in substantially the form indicated in Figure '1, where the position of the supply rolls 24 and 25 may be shifted rearwardly or to the right of the apparatus and their respective webs 26 and 29 guided along paths not thermally related to the drums, as by suitable guide rolls .6D and 6|, respectively, and to bring them into operative relation to the parallel conductors 36, with web 29 brought above the conductors and web 28 below the conductors, thus to enter the three-fold entity comprising the two webs with the parallel spaced conductors between them, into operative relation to the drums 2l and 21.

The drums 26, 21 are driven by any suitable means so that their adjacent portions move in the same direction, in the direction toward the left in Figures 1, 6 and 7, and preferably at the same surface speeds, and preferably at a surface speed the same as the speed or rate of linear movement of the conductors 36 which, with one sheet material 29 overlying them and the other sheet material 28 underlying them, are to have their assemblage completed by the action thereon of the drums 26, 21. For thus driving the drums, any suitable means may be employed, such' as a shaft 63 (Figure 2) driven from any suitable source of power, not shown, and geared as by pinion 64 to a gear 65 on the shaft of drum 26 and, in turn, being in driving connection, as by suitable gearing 66 with the shaft of drum 21, the gearing being arranged so that, as viewed in Figures 1, 6 and 7, drum 21 is driven in clockwise direction and drum 26 in counterclockwise direction.

'I'he rate of movement of the conductor or conductors 88 toward the left ymay be determined and the movement effected by any suitableN means, such as for example, by a capstan sheave or sheaves 69 driven in any suitable way, as by shaft 18, preferably at the same surface speed as the surface speed of the drums 26-21, and hence may be synchronized with thev drive of the drums in any suitable way, not shown. The capstan sheaves 69 are preferably aligned with the guiding means 52, Figures 1, 6 and 7, so that, at the desired tautness, as may be determined by the braking means associated with the reels I, the plurality of conductors 36 lle in the same plane which passes intermediate of the two drums 26-21., are given the desired spacing,

preferably equal spacings, one from each other,

as indicated in Figure 8, for example, and, where the partial preshaping or uting is employed, the flutings in each web, as above explained and as will now be clear, are spaced center line to center line according to the spacing between the conductors 36, as indicated in Figure 8. Y

The drums 26, 21 of Figures l, 6 and '7 are constructed to act upon the thermo-plastic material of the sheets or webs 28, 29, to effect certain actions which will be clear after consideration of a preferred form of construction of the drums 26, 21.

Thus, I arrange to maintain the operative portions of the drums at a, temperature suited to the particular thermo-plastic characteristic of the sheet material employed, as is later set forth ln greater detail and a preferred arrangement for supplying heat to the drums 26, 21, comprises constructing the drums to be hollow and supplying the interior space thereof with a suitable heating medium, such as steam, or a heated liquid like oil.

Thus, for example, as indicated in broken lines in Figure 2, the hollow space 26al within drum 26 may be supplied with heating medium through a hollow shaft or trunnlon 13 through which, and preferably coaxially therewith, extends a smaller-diametered pipe or conduit 14, the one serving as an inlet passage and the other for an outlet passage, so that the heating medium may be continuously passed through the drum to keep its cylindrical shell and the operative portions thereof at the desired temperature,

In a similar way, the interior 21a of drum 21 may have a hollow shaft or trunnion 16 through which extends a smaller-dlametered pipe 11. The hollow trunnions and the tubes or pipes that extend through them are connected into the circulating system of the heating medium by any suitable means, such as conduits or piping 19 connected to the outer ends of the pipes 14 and 11 as by suitable stuiling box or gland connections 80, with suitable valve controls 8|, while the hollow shafts 13 and 1,6 are connected by piping or tubing 83 through suitable stuffing box or gland connections 84, preferably including also valve controls 85. In detailed construction, these connections may be given any suitable known form. Thus, during rotation of the drums, they may be continuously supplied with a fluid heat-v ing medium and any suitable means, illustratively the valves 8| and 85, may be used and thermostatically controlled to govern the rate of flow and temperature input of the heating medium and thus suit the rate at which heat is supplied to the operative portions of the drums to the functions which they are to perform upon the thermo-responsive material of the webs and according also as the latter may, or may not, be

' pre-warmed or pre-shaped.

ple, rounded off or chamfered somewhat to avoid presenting sharp corners or edges.

The operative annular elements 26h, 21h, are preferably of radial dimensions greater than the maximum vertical radius, as seen in Figure 9,

of the assembled conductors and sheet material,

or may be otherwise shaped or constructed, as by providing annular spaces 26, 21, respectively, between them and of a depth or cross-sectional shape or dimensions preferably to avoid substantial pressing or engagement of the side or bottom walls of the annular yspaces against or with the sheet material below and above the conductors, as viewed in Figure 9, as will become clearer later hereinafter.

In axial dimension, the faces 26, 21 of the annular elements 2,6", 21h, respectively, are preferably equal to a factor which is the dimension of the actual space between two adjacent conductors less twice the thickenss of the sheet material of the webs 28, 29. The drums 26, 21 are preferably mounted in the frame elements 28, 2| (Figure 2) to be vertically adjustable, preferably toward or away from one another, in any suitable manner, as by the hand-Wheels and screws 2liEL and 2l (Figure 2) operating upon the slidably mounted bearing blocks carrying the drums and as indicated by the arrows in Figures 1, 6 and 7, it being understood that the drive of the two drums and the connections thereof to the circulating system are constructed in any suitable way to allow for such adjustment. The drums are set so that the spacing, as viewed in Figures 2 and 9, between companion operative faces 2lic and 21c is less than the sum of the thicknesses of the two sheet materials 28, 29, and by way of illustration, it being noted that the sheet materials 28, 29, are, preferably of equal thicknesses, this spacing may be on the order of one-half of the sum of the twothicknesses. Thereby I insure that, as the three-fold entity of conductors 36 with the sheets or webs 28, 29 pass in between the drums, the portions of the two sheets intermediate of the successive spaced conductors are subjected to pressure, and in the preferred arrangement, the annular operative elements 26b and 21D, being heated to the desired temperature, communicate heat only to these intermediate portions of the two sheet materials, while under pressure.

As will be seen upon viewing Figures l, 6 and 7, the throat formed by the operative elements of the drums 26, 21 converges or gradually narrows itself, so that the action of the companion pairs of heater and presser elements 26, 21b is in effect a gradually progressive action, and where these elements are constructed in rotary form, as in the preferred embodiment, their movement inwardly toward the narrowing or narrowest portions of the throat effects a progressive action, which, among other things, effects fluting of the two webs or sheets about the respective upper and lower half-cylindrical surfaces of the conductors where preliminary iiuting is not utilized as in Figures 6 and?, or completes the proper iluting or laying of the sheet materials against the two longitudinal upper and lower half surfaces of the conductors, where the preliminary iluting or so-called pre-shaping, as in Figures 1 and 8, is utilized.

Thus, in Figure 11, I have indicated somewhat schematically an earlier stage of the action of the presser and heater elements, such as the action that takes place at that portion of the converging throat where the companion elements 2Gb and 2'!b have a spacing of about the sum of the thicknesses of the twosheet or web materials 28,29, so that the portions 2li` and 29 thereof that are intermediate of any two successive conductors 36 have their adjacent faces brought just about into engagement with each other. It will be understoodthat,jv because of the preferred shaping of the-throatl and, particularly, where pre-flutingis not resorted to, these intermediate portions may be engaged by the heated presser elements, earlier than the stage indicated in Figure 11, depending upon the `angles at which the webs 28, 29 are fed to the throat relative to the line or plane of the conductors 36, thus receiving heat therefrom at an earlier stage. The heat flows into the portions 28, 29, and as the threepart entity of sheet materials 29, 29 with interposed conductors 36 continues to move to the left, as viewed in Figures 1, 6 and 7, and beyond the stage indicated in Figure l1, the throat continues to narrow up, and the now heated portions 28, 29 become compressed and pressed against each other, to a greater and greater extent until the narrowest portion of the throat is reached, by which time maximum heat and pressure effect by the elements 2Eb and 2lb upon the portions 28 and 29, respectively, has been accomplished.

Where the minimum spacing between the presser and heater elements is, in dimension, onehalf of the sum of the equal thicknesses of the sheet materials 28, 29, the above-mentioned final stage of heating and compression nds .the structure somewhat in the relationship shown in I'gure 12, where it will be seen that the portions 28 and 29 have been reduced in thickness and, in the assumed illustration, have been reduced to one-half their original thickness.

Accompanying these physical actions, the heat transfer to the portions 28 and 29 has been of such magnitude that the material, due to its thermo-plastic characteristics, has throughout the regions of the portions 28, 29 become soft and in effect plastic, and under the pressure effect, plus its condition of mobility due to its temperature, the materials of the two portions 28 and 29 practically flow or merge together to effect a bond or union. The heating of the portions to be bonded is preferably to a temperature just below or approximating the melting point of the particular material employed in the sheets or strips 28, 29.

The now bonded portions 28, 29 emerge to the left, as viewed in Figures 1, 6 and '7, from the narrowest portion of the throat and hence come out of heat transferring contact with the heating and pressing elements, the latter, being cylindrical and rotary in the preferred form, and providing to the left an exit throat which is divergent, thus to permit the moving conductor assemblage to come out of direct contact with the 75 heater and presser elements, whence cooling ofi commences. Further cooling off is also effected by the absorption of heat by the metal of the conductors themselves which, when made of oopper, as is usually the case, have a high heat capacity, or the cooling may be accelerated as later described.

In these actions, I make it possible to avoid stretching of the arcuate portions 28b and 29b of the sheets 28 and 29, or if stretching does take place, it is of inconsequential magnitude or effect. Thus the progressive compression of the intermediate longitudinal regiong 28, 29 in passing from the stage of Figure l1 to the stage of Figure l2 is accompanied by the substantial heating action and causes the material, being now substantially plastic or mobile, to move to the right and left, as viewed in Figure l2, and hence so much of it as cannot be accommodated in the progressively narrowing and in the finally narrowest space between the faces llc, 21 of the elements 29 and 21h, respectively, is forced out from in between these faces and, in eect, adds itself equally to the arcuate portions of the sheets, thus counteracting tendency to stretch or tensioning in these arcuate portions 29", 29b or, in effect, relieving any material tension that might be present therein. This mobility of the material to extend itself in directions to become part of the arcuate covering portions practically ceases upon emergence of the assemblage from the narrowest portion of the throat, whence cooling off takes place.

Thus, companion portions of the two sheets become laid against the two respective convex halves of the conductors, but without adhesion or bonding to the latter and with a looseness of fit, as indicated at I, that gives adequate leeway for possible shrinkage of the material of the casing of each conductor while retaining the capacity for relative ease of relative movement between the conductor and its immediate casing, particularly upon bending or curving. Though the material of the portions 28, 29 is, during the process, practically plastic under the heat effect, I have found that those portions that have some mobility or are plastic or owable under pressure and which might be in engagement with small regions of the conductors adjacent the junction formed between the portions 29, 29, do not adhere to the conductors, apparently because a sufficiently high degree of plasticity does not exist where direct contact of the material with the conductors might take place or perhaps because the metal of the conductors removes the heat from any otherwise suiliciently plastic material in contact with the metal as to reduce its mobility or plasticity to a degree below that causing adhesion.

The temperature to which the strip materials are heated are, as above pointed out, preferably below the melting point of the particular material employed. For example, where the melting point of certain formulations of Koroseal" is 160 C., the heating of the portions 28 and 29 by the heater and presser elements is on the order of C. It will, of course, be understood that this temperature may be varied to suit the particular circumstances; for example, at slower speeds of movement through the heater and presser elements, a slightly lower temperature of heating might be employed. Also other factors, such as the amount or character of plasticizer employed may affect the temperature to which the heater and presser elements are made effecitial characteristics of the material that was tive upon the material. But with an apparatus like that above described, and for any desired or selected composition or formulation of the material oi' the sheets or strips employed such as, for example, Vlstanex, Vinilite," Formvar, etc., the temperature of heating may be comparatively quickly determined empirically. For example, certain synthetic formulations have a tendency to, or characteristics of, disintegratlng or sugaring when heated to a certain degree, and, in such case, care should be taken to determine the temperature at which the sealing together or bonding is to take place at a value below the disintegrating temperature. Others, like Koroseal, I have found exhibit a range of temperature within which the bonding or sealing action may be eiected, other conditions such as thickness of the material, speed of movement thereof, etc., being correspondingly suited to any selected temperature within such range; thus, with Korcseal of a formulation containing about 40% of plasticizer and having a melting point of approximately 160 C., I have found that it bonds together fairly well at 141 C., makes a satisfactory bond at 147 C., and practically welds or melts together at approximately 150 C., operating upon strips or sheetshaving a thickness of 0.015. Others have relatively fixed heating points or narrower ranges; for example, with Formvar the bonding temperature is substantially critical, being, I have found, `lust about 100 C.

I am thus enabled, according to the thermoplastic characteristics of the material employed, and without having to have recourse to slow, cumbersome and costly vulcanization of the vulcanizable rubbers, either synthetic or natural, to achieve dependable encasing of the conductor or conductors, and, according to circumstances, the junction effected between all of the pairs of longitudinally extending portions 28 and 29, as in Figure 12, may vary somewhat in character; thus the junction may be effected, under the heating and pressure eiect, by what is in the nature of a bond brought about by tackiness or adhesiveness during the heating and pressing, or it may be in the nature of an .actual iiowing together or fusion of the heated mobile masses of material in the portions 28a, 29B, depending upon such factors as the heat and pressure employed and the nature of the particular material employed. In the former case, there may be present in the final structure as it emerges from the stage shown in Figure 12 and after it has been cooled, a perceptible plane, suggestive of a plane of cleavage, between the bonded-together parts 28a, 29, and in the latter case such a plane is hardly, if at all, perceptible or present.

Preferably, I provide means for more effectively and quickly cooling off the multiple insulated conductor structure, upon its emergence from in between the heater and presser elements and hence upon its emergence from the stage indicated in Figure 12. Thus, forr example, I may provide for blowing air onto the upper and lower sides of the multiple conductor structure and into the respective angles which it forms with the drums 26 and 21, as by suitable air guiding means or jets 88 and 89 as indicated in Figures 1, 6 and 7, or I may run the structure through a liquid cooling bath diagrammatically indicated at 9|, or both, thus restoring the heated portions of the webs, now assembled together and to the conductors, as above described, to their initial or room temperature and thus restoring the inheated, such as its pliancy, strength, toughness, capacity of stretch, and the like, whence, if desired, the multiple insulated conductor structure may be put into use, orii' desired and according to certain other aspects of my invention, may be further processed as is later hereinafter described.

As a multiple insulated conductor structure, it may comprise any number of conductors, of which only two are shown in Figure 12 and, illustratively, but not by way of limitation, 200 conductors 38 may in such a single operation be so enveloped or encased between two web or sheet materials which, if the process is carried on even at as slow a rate of movement relative to the heater and presser elements as 25 feet per minute, results in a production of linear footage of 5,000 feet of insulated individual conductor per minute.

The resultant band-like form of structure or desirable longitudinal sections thereof, may be employed as such, is characterizedfby great ease of pliancy, longitudinally, and hence readily adaptable to attachment 'flat-wise to surfaces, being capable of repeated bending into and about corners, curves, angles and the like. In this latter connection, the relative ease or freedom of relative movement between each conductor and its individual casing makes such application to repeated bending or curving when applied to broken or irregular surfaces, possible, in that conductor and casing are, independently of each other, accommodated to the bend or bends and hence setting up and multiple'compounding of harmful strains in the conductor or casing, particularly where the conductor is stranded, do not take place due to this ease of relative movement,

This easeof relative movement and freed-om from adhesion between the conductors and their enclosing insulation also makes possible the ready stripping or baring of the individual conductor or conductors at the end or ends of a run or length of lthe insulated conductor structure. This may be quickly accomplished by stretching, as by pulling, the multiple casing structure beyond the already cut-off ends of the conductor and cutting it oi, whence the recovery of the material due to its elasticity causes the cut-off end of the casing to recede from the ends of the conductor or conductors, thus the latter; or, before cutting the multiple conductor structure, the casing part thereof may be stretched relative to the conductors, and when both the conductors and the stretched casing are then cut, the recovery of the casing causes its cut end to recede from the out end of ythe conductor or conductors, thus baring the latter.

There is also present wide exibility transversely of the band-like structure, flexing taking place in the regions of the joined-together longitudinal portions 2B" and 29, as seen in Figure 12, and the structure may be folded or rolled up about these joined-together portions as axes of transverse bending. Along these portions also, the structure may be slit or cut, to divide it, or only portions of its length, into two or more branches, each of one or more insulated conductors and the branches may be cut, oif at such lengths as may be desired, the stretchability and recovery of the casing material in conjunction with the above-mentioned ease of re1- ative movement between the casing and the conductors greatly facilitating the stripping or baring at the ends.

Moreover, great compactness can be achieved. For example, and in dimensions, using #16 stranded conductor, having a, diameter of 0.055, and a sheet material of 0.015.,it will be seen that the thickness of the band-like multiple insulated conductor is increased by only 0.030" and the actual spacing between adjacent conductors may be on the order of 0.060", where the heater and presser elements 261 and 2lb of Figures l1 and 12 are given a transverse dimension or thickness of twice the wall thickness of the sheet material itself.

I make provision also, as above indicated, for continuously separating encased conductors into single conductor, two conductor or other multiple conductor units to thus provide insulated conductor or conductors for general wiring applications or to form lamp cords, circuit extension materials, etc., or to form the basis for a built-up insulated conductor structure such as armored cable, so-called non-metallic sheathed cable, and the like.

Here I prefer to provide, referring now to Figures 1, 6, 47 and 10, a heated parting or severing element, one for each line of severance t be effected and, in the above assumed illustration, one for each of the longitudinally extending joined-together portions 28, 29*I (Figure 12) of the structure, spacing them correspondingly transversely of the plane of movement of the conductor structure toward the left, and, as better appears in Figure 10, and because of the relatively small spacings, these heated parting elements, each generally indicated by the reference character 92, may be staggered. Each may comprise (Figures 1, 6 and '7), a blade-like member 93 and a heater element 94 therefor, the latter being preferably any suitable form of electrical heating unit provided with any suitable means, such as a rheostat, for controlling or setting its heating action, or effect.

Each heater parting element 93 is maintained at a temperature that is preferably at, or somewhat above, the melting point of the particular formulation of the sheet material employed. Thus, in the case of Koroseal, a temperature of 160, if that is the melting point, or preferably slightly above, is made effective, and as the composite or multiple` structure is drawn along, as by the capstan sheaves 69 operating upon the separated insulated conductors, with the heater and parting elements 93 positioned to operate in a vertical plane, that is, the central plane of the joined-together portions 28a and 2S, the material of these two portions to each side of the heater and the parting element 93, in each case, is raised to a temperature on the order of the melting point of the material of the sheet employed, or slightly above it, thus greatly easing and facilitating the parting action and, at the same time, causing a fusion or flowing together of the respective halves of the portions 28a and 29a there- `by completely or sufficiently eliminating any plane of cleavage therebetween and resulting in longitudinal junctions of the arcuate covering portions 28b and 29", somewhat as indicated in Figure 13, as at 96.

While still heated and in somewhat mobile state, theexternal surfaces of the junctions 96 may be smoothed down, crimped or ironed out by any suitable means, such as presser or roller elements 91 (Figure 10) and when any such longitudinal protrusions are thus or otherwise removed or ironed out, the resultant casing for the individual conductors 36 appears somewhat as indicated in Figure 14. Immediately thereafter, I prefer to withdraw the heat from the l heated Junction portions and here I may employ a cooling liquid bath, as indicated diagrammatically at n, in Figures 1, 6 and 7, whence the now individual insulated conductor structures pass, respectively, over their capstan sheaves 68 and l onto their respective reels 96.

:ill

Should it be desired to produce insulated paired conductors,v such as for lamp cord, for example, the heater and parting elements $2 are positioned so as to operate upon every alternate Joined-together portions 28` and 29, whence the former band-like multiple conductor structure emerges from. the heated parting elements in pairs of conductors, joined together as indicated in Figure 15 where two such pairs are shown, and thereafter chilling of the junctions 96 may be proceeded with, with or without smoothing off, or ironing out, of any longitudinal protrusions representing the junctions 96.

It might at this point be noted that, where the particular formulation or composition employed in the strips or sheets, has a tendency to shrink when elevated to high temperatures, the cooling or chilling actions above mentioned work in opposition to such shrinking action and this opposition or counter-effect, effected by withdrawing heat from the sheet material, may be materially aided by the rapid withdrawal of heat by the metal of the conductors which enter the apparatus in unheated condition or which may, if desired, even be pre-cooled by any suitable heat exchange means, indicated diagrammatically, in Figures 1, 6 and 7, at IUI; the means or device 10| may take any suitable form such as a cold air blast, or the like, through which the conductors 36 are passed or into thermal-relation to which they are brought in any suitable way. The absorption of heat by the metal of the conductors, during the relatively short time interval that the strip or sheet materials are undergoing heating by the heater and presser elements, thus protects the walls formed by the sheet material about the conductor from being raised t0 a high enough temperature, to let any shrinking eiect become of material consequence, insofar as maintaining relative ease of relative movement between the individual conductor and its casing is concerned.

In giving the heater and presser elements shapes or conformations like those described above in connection with Figure 9, in that the heated presser elements preferably do not come into contact with the arcuate or semi-circular portions of the sheet material, like the portions 28h, 29h, of Figures 11 and l2, direct heat transmission to these portions is avoided, and thus raising of the temperature of these portions in that manner cannot take place and the shrinking tendency, if present in the particular material employed, is thus also not encouraged.

The method and apparatus readily lend themselves to meet particular situations or requirements. Thus, Ifor example, where it is desired to produce the multiple insulated conductor structure, in band-like form, without slitting or severing, leaving the parting of one 0r more insulated conductors from each other or from the rest, to be done in the field, as by a knife or scissors, it may be desirable to have the joined-together portions 28a, 29*i of Figure 12 of greater width, and in such case, the heater and presser elements are constructed to have their opera.- tive faces 26c and 21 of Figure 9 of greater width as viewed in that figure, the spacings center to center of the conductors 36 being correspondingly or appropriately increased.

However, I prefer to provide for greater ease of parting or separation, as by cutting with scissors or a knife by effecting, at the center of the Junction represented by the portions 28, 29 of Figure 12, a region or zone in which the bonding or flowing together is, either entirely absent, or is weaker mechanically than to either side of that zone. This I may effect by shaping the heater and presser elements 26 and 21h of the drums 26 and 21, as shown in Figure 16, which otherwise corresponds to Figure 9, and as shown in larger scale in Figure 17, which otherwise corresponds to Figure 12, where the operative faces 26 and 21 are, throughout their peripheral extent, centrally grooved or concaved as at 26'r and 211, respectively.

With such a conformation, and bearing in mind the actions that take place under the heat and pressure effect as was above described in connection with Figures 1l and 12, I achieve throughout the regions of the portions 28, 29, that are, due to the shaping of the faces 26 and 21 subjected to the maximum compression, a

bonding or flowing together of the materials as was described above in connection with Figure 12, but in the central region of the portions 28, 29, that is, the regions thereof that are between the grooved or concave portions 26K and 21z of the presser and heater elements, a bond that is relatively weak, and in a sense, varying probably with the degree of compression, or practically no bond at all where the concavities or grooves 262 and 21g are deep enough or otherwise shaped to transmit insuilicient heat or pressure, or both, to effect adhesion, bonding or flowing together.

Thus the junction between two adjacent conductors 36, whether made up in units of two as in Figure 15, or made up in greater multiples, as in Figures 9, 12 and 16, may in cross-section appear substantially as in the somewhat exaggerated View of Figure 18, where throughout the general regions or zones A and B the portions 28 and 29a are securely joined together by actions like those described above in connection with Figure 12, being brought about by the pressure and temperature effects produced by the coacting or juxtaposed marginal portions of the heater and presser elements 26b and 21b of Figure 17, while the central or intermediate zone indicated at C in Figure 18, of the portions 28 and 29l are but weakly joined or, as indicated` in Figure 18, in somewhat exaggerated form, are not joined together at all. In either case, the cutting is greatly facilitated, whether that be done in the iield as by a knife or scissors, or whether that be done in subsequent steps of my process, as by the heater and parting elements 92 of Figures 1, 6 and 7. This central zone C, extending longitudinally and centrally between the two parallel conductors, also acts, because it presents less resistance, as a guide, or to centralize the path along which the cutting or parting device or devices operate, and thus better uniformity of separation is achieved and risk of having the device run into a conductor casing is lessened.

It may be desired, instead of curving portions 26h and 29b of the sheet material about the respective sides of the conductors, to have the sheet or web element of one of them, such as the sheet material 28 flat, or substantially flat,

and to loop the companion sheet or web material, such as/the upper one 29 about the parallel spaced conductors. In such case, I may retain the configuration of the upper heater and presser elements, as by retaining the drum 21, as shown in Figures 1, 6, 7, 9 and 16, and as for the companion drum 26, I may reduce the height or radial dimension of its heater and presser elements 26D to any desired extent as, for example, as shown in Figure 19 where they have a height just about sufficient to localize the pressure and heating to the regions 28, 29 between corresponding or juxtaposed heater and presser elements 26, 21, giving the latter operative faces shaped as described in connection with Figure 11, or as in Figure 17, or any other suitable contiguration. In such case, the structure and junctions eected appear substantially as shown in Figure 20, it being understood that pre-shaping of the lower web 28 is not resorted to and where the arrangement of Figure 1 is employed, the tluting device 34 may thus be omitted.

If, in making the structure of Figure 20, it is desired to effect a junction between the casings of adjacent conductors like the junction shown in Figure 18, it will now be clear that, as shown in Figure 21, appropriate shaping of one or both of the companion heater and presser elements according to the shaping shown in Figure 17 may be provided and for purposes of illustration I have in Figure 21 shown the elements 21b shaped as was described in connection with Figure 17 and in Figure 21 is also indicated the general type of junction described above in connection with Figure 18. Where only one of the companion heater and presser elements is shaped to effect, in coaction with the other one, a lesser or no amount of compression as along the central zone C of Figure 18 or Figure 21, it is preferable to increase the depth of the concavity as at 21 in Figure 21.

As with other forms, such as those earlier above described, the form of multiple insulated conductor construction of Figures 20 and 21 may be further processed, if desired, as by effecting parting of encased conductors singly or in multiples as described above in connection with Figures l, 6 and 7. The structure of Figures 20 and 21 may, however, be further processed to produce a structure like that shown in Figure 22.

For purposes of illustration, the structure of Figure 22 is shown as a two-conductor structure though it will be understood that the essentials or advantages may be realized where greater multiples than a single pair of conductors is desired.

In making up the structure of Figure 22, I carry on my process as described in connection with Figures 20 and 2l and, preferably by utilizing the heated parting elements 93 of Figures l, 6 and 7, I rst produce a two-conductor structure as it appears in Figure 20 or Figure 21, disregarding for the moment that those figures are fragmentary or partial views of the structure in greater multiples than two, and then I fold the two-conductor structure longitudinally about substantially the central plane of the joinedtogether portions 28a-298L as an axis, thus bringing the substantially fiat casing portions 28h-28b of the two casings substantially ilatwise against each other and then join together the overlapping end or edge portions 2828k by a junction indicated in Figure 22 at 28m.

This junction 28rn is preferably formed by a suitable heated implement or tool which raises the temperature of the end or edge portions 2|3L28k to cause the material thereof to bond or merge or flow together, by an action similar to the action above described in connection with the heated parting elements 93.

The resultant structure as shown in Figure 22 may then serve as a two-conductor insulated structure, such as a so-called lamp cord, and in the absence of a junction throughout the adjacent faces of the portions 28h-28h, also as indicated in Figure 22 by the transversely extending cap or space Y, parting of the structure, as at the ends thereof where the respective conductors are to be bared for making electrical connections, may be readily effected without impairment of the individual insulating casings of the conductors. g g

The internal space or cleavage Y extends throughout the length of the structure and serves as a guide for a knife, scissors or other tool that it may be desired to employ to effect separation of the two insulated conductors, the cutting being effected along the plane of the cleavage Y and, of course, through the junction 28xn and through the folded-over joined-together portions 28a-29a.

The junction m may be effected in a continuously carried on step as is diagrammatically indicated in Figures 23 and 24 in which any suitable means such as take-off reels and capstan reels (not shown) may be utilized to effect substantially continuous movement of the multiple structure already folded over longitudinally in any suitable Way, thus to present the laid together longitudinally end or edge portions 28k-28k, as they continue to move, to a heated implement |03, maintained at the desired temperature in any suitable Way as by an electric heating unit |04. Any suitable means may be employed to hold and guide the folded-overstructure relative to the heated junction-forming implement |03, such as rollers |05 suitably distributed on the two sides of the moving structure, as indicated in Figure 23, and preferably with one of them in juxtaposition to the heated element |03, thus dependably to .back up the moving structure during action of the heated element |03 upon the portions 28k-28k.

Conveniently, the rollers may be shaped as indicated in Figure 24 to have a configuration fitting the configuration of the folded-over structure and preferably with end flanges of sulcient radius to overlie the upper and lower portions of the folded-together structure as shown in Figure 24 and thus to hold its two portions against un-folding and to maintain the edge portions 28k-28i in close engagement so that their material, when heated, for example, to or in the neighborhood of its melting point, will iiow together to achieve the junction desired.

The roller |05 to the left of the element |03 in Figure 23 may serve as a smoothing or ironing out roller, like the devices 91 of Figure 10, and preferably also the completed junction is chilled or cooled as by passing it through a, cooling bath indicated at |02.

Each longitudinal edge portion 2|lL---28k comprises longitudinally severed but joined-together portions 28h-29* so that, irrespective of the particular character of their junction as previously elected, the heated implement |03, may not only merge or ow together the material of the composite edge portions 28k-28k, but also merge or iiow together the material of the erstwhile components 2B29a thereof.

It will be understood that, in carrying on my method as above described, all of the conductors 36 that are operated upon simultaneously, or in one bank, need not be of the same size throughout; for example, it may be desired to produce several sizes of insulated conductor construction such as, for example, conductors of gauge numbers 14, 16 and 18, and this may be done in the same run. In such case, the several sizes of conductor are preferably divided in groups, for example, equally, and thus about one-third of the conductors 3B may be of one size, the next or middle group may be of another size, and the remaining third, or outside group, of another size. Or, for special or other desired purposes, other groupings of different sizes may be effected.

According to whatever grouping is selected, the heater and presser elements, of whatever form they take and certain of which are illustratively set forth above, are given corresponding spacings, according to the different diameters of conductor and the thickness of the encasing material and, where desired, they may be given effective or operative contact faces of different widths according to the transverse spacings desired, axis to axis, of the parallel encased conductors. Where pre-shaping or preliminary fluting, as with a device like that of Figures 3, 4 and 5, corresponding spacings in the fluting devices are provided and they may be otherwise con formed to the required circumstances as desired.

Where greater flexibility of control or of range or capacity to handle different size spacing or like requirements are desired, I may construct the heater and presser elements as shown in greater detail in Figures 9 and 9l in which the annular elements 26b and 21b are preferably not integral with their respective supporting drums 28 and 21, and are constructed to be sleeved or slipped onto 40 their drums in groups or sequences to provide the various dimensional and space requirements or conditions desired. Preferably, the annular elements 2B and 21b have associated with them an annular part such as the parts 2li1 and 21f, respectively, for achieving the desired spacing axia1- ly from one another, and in the illustrative and preferred construction the element 2Gb and ele-` ment 26f are integral as are also the parts 21b and 21f.

The parts 26r and 21f may thus serve as sleevelike or hub-like supports for the annular heater and presser elements 2B and 21, respectively, for snug reception onto the cylindrical surfaces of the drums 26 and 21, respectively, thus also to insure dependable heat transmission. Any suitable means may be provided to hold them assembled to their respective drums and also to hold them against rotation relative thereto. Thus, as is indicated in Figure 2, the left-hand-ends of drums 26, 21, may be provided with an annular flange or abutment 2Sh and 21h, respectively, 4against which the left-most elements sleeved onto the drums respectively rest, While the right hand hand of these drums may be provided with any suitable clamping means such as the clamping rings |06 and |01 threaded onto suitably threaded end portions of the drums and operated as by a Spanner wrench. Preferably also, the drums carry keys |08 and |09, respectively, to take into suitable keyways in the annular sleeve or hub parts, thus to effect a spline and hold the sleeved elements against rotation relative to their drum supports.

The units 26f and 2Gb and 21{ and 21b may be constructed of various axial dimensions and assembled to their respective drums in groupings or sequencies according to the requirements to be met. Thus, for example, in Figure 9 it has been assumed that the conductors 36 are all of the same size and that the transverse dimension or 5.

axial dimensions, thus giving the structure heater* and presser elements 2Gb and 2lb that are all ,of the same axial dimension, with the axial spacings therebetween, to provide the spaces 28 and 21, all the same.

But in Figure 9a there is represented an il1us' trative grouping of units of different axial dimensions to meet a different requirement or condition, and let it be assumed that it is again desired to have the transverse dimensions of the joinedtogether portions 28e- 29'l all the same through' out, the units assembled to the two drum supports have heater and presser elements26b and 2`Ih of the same axial dimension, but have hub or spacer portions 26t and 21f of different axial dimensions according to the different sizes of conductor to be operated upon, thus to vary the axial dimensions of the spaces 26e and 21e accordingly. Illustratively, the conductors 36 of the left-hand group oi' three are of one size and the axial dimensions of the hub and spacer parts 26f and 21'- are correspondingly dimensioned; the conductors N of the middle group of three are of a smaller size and the hub portions of the corresponding units are accordingly of lesser dimension, while the conductors 36 of the right-hand group o1' three are of largest size and hence the hub and, spacer portions are of correspondingly greater axial dimension. By providing units or elements in which the axial dimension of the heater and presser elements 26b and 21b are different, as may be desired according to circumstances, I am enabled to make up an assemblage to meet also any needs for different transverse dimensions or widths for the joined-together portions 28-29'-, mi well as for different sizes of conductors. For any given run of the method and apparatus, any particular requirementl may thus be dependably met by making up on the drums of Figures 1', 6, 7, 16 and 19 such a combination of individual units as will meet the particular requirement, it'

being understood, of course, that the apparatus is constructed in any suitable way for the ready detachability of the drums therefrom, or otherwise, to facilitate replacement, change or rearrangement of the units carried by them.

Depending upon various circumstances or factors, illustrative ones of which are later mentioned herein, I may carry on my method to advantage, by physically segregating the performance of the two steps corresponding to the two stages or steps shown in Figures 11 and 12, and this mode of carrying on my invention will become clearer upon consideration of a preferred form of apparatus therefor, as shown in Figure 25. In Figure 25, the apparatus is physically substantially the same as that described above in connection with Figures 1, 6 and 7, but I have provided two sets of coacting elements to effect the heating and pressing actions, and arrange them so that the first set, in whatever form they take, effects heating of the portions 28* and 29u preferably accompanied by some pressing of Athem together while the second set is arranged immediately thereafter to apply the ilnal or junction-completing pressure to the already heated companion portions 2l* and 26; in effecting such practice oi' my invention, certain advantages and improved actions are achievable.

For purposes of illustration, let it be assumed that the duplicated coacting elements are in the form of two sets of lower and upper drums 26-21 with annular operative elements 28 and 2lb, respectively, constructed as above described in connection with Figures 1-20 and in Figure these duplicated units are both represented by the same reference characters 26-21, being preferably structurally identical with each other and with the units 28-21 earlier above described, but in Figure 25 I have distinguished them by designating them, in order from right to left, as unit A and unit B.

To unit A, the conductors 36 and the strip or web elements 2l--2l are fed as was above described and as indicated in Figure 25, utilizing the pre-shaping devices 34-36 preceded by pre-heating of the webs if desired, while, as in the case of Figure 1, the pre-iluting may be dispensed with by simply swinging or setting the fiuting elements lll-4I apart from each other to bring and hold them out of operative relation to the strip material. Pre-heating, i! undesired, may be dispensed with by inserting removeable heat bales or barriers II2 and ill, thus to cut on the ilow of heat from the drums 26-21 of unit A to the web elements and 2l, respectively.

Through drums 26-21 of unit A is circulated or passed a suitable heating medium as described above in connection with Figure 2, but the setting of or spacing between the faces 26, 21C, of the elements 28h and 2lb, respectively, whether they are shaped as shown in Figure 11 or as shownl in Figure 17 or as may otherwise be desired, is such that, at their points or places of nearest approach is on the order of that shown in Figure 11, being preferably slightly less than the sum of the thicknesses oi' the strip elements 28 and 29 so that the heated portions 28 and 29* as seen in Figure 11 are pressed together to some extent and preferably to an extent just about sumcient to cause these two portions to have some adhesion, one to the other or. where the heating is of a magnitude, as in the preferred case, to give the material of the portions 28a-29l some mobility, the pressing of the two portions toward each other is relatively slight and just about enough to merge the mo-V bile materials together at their planes or surfaces of contact, whence the three-fold entity of conductors 36 and strip elements 28-29 emerge from unit A in that condition.

While the elements 2Gb and 2'Ib of unit A are operating upon their respective sheet elements 2l and 28, they thus effect transfer to the portions 28-29L of the desired amount of heat to bring the materials of these portions to the desired condition as earlier described, it being noted that the extent of arcuate contact, for heat transfer, may be varied according to the angles at which the strip elements 2B and 2l enter the throat with respect to the plane of the conductors 36.

Immediately upon emergence from unit A and at the left thereof as seen in Figure 25, the above-mentioned three-fold entity enters the throat formed bythe elements o! unit B, and the parts 26 and 21 of unit B are set so that the operative faces of the annular elements 2lb and 

